The invention relates to a method for mounting a hydrodynamic sliding bearing of a shaft, in particular a magnetic coupling pump, wherein the hydrodynamic sliding bearing comprises a bearing bushing disposed between a bearing sleeve and a bearing housing. However the invention also relates to the hydrodynamic sliding bearing itself.
Magnetic coupling pumps are generally known and described, for example, in DE 10 2009 022 916 A1. In this case, the pump power is transmitted from a drive shaft via a magnet-carrying rotor (outer rotor) in a contact-free manner and substantially free from slippage onto the pump-side magnet carrier (inner rotor). The inner rotor drives the pump shaft which is mounted in a sliding bearing lubricated by the conveying medium, i.e. in a hydrodynamic sliding bearing. Located between the outer rotor and the inner rotor, i.e. between the outer and the inner magnets is the split case with its cylindrical wall. The split case is connected with its flange to a pump component, for example, a casing cover and has a closed base opposite thereto. The split case, i.e. the magnetic coupling pump reliably separates the product case from the environment so that the risk of an escape of product with all the associated negative consequences can be eliminated. A magnetic coupling pump is accordingly the combination of a conventional pump hydraulics with a magnetic drive system. This system uses the attraction and repulsion forces between magnets in both coupling halves for the contact-free and slippage-free transmission of torque. The magnetic coupling pump accordingly has major advantages particularly when handling very valuable or very hazardous substances.
EP 0 814 275 B1 is concerned with a hydrodynamic sliding bearing of a magnetic coupling pump which is configured as a combined axial and radial bearing. The sliding bearing of EP 0 814 275 B1 has two bearing sleeves, two bearing bushings which are slidable on the bearing sleeves, a spacer sleeve disposed between the bearing sleeves and a spacer bushing disposed between the bearing bushings. The bearing sleeves and bushings are made of a ceramic material, where the spacer sleeve or bushing is formed from a metal. In order to create a hydrodynamic sliding bearing which should be inexpensive to manufacture and designed so that at all times sufficient lubrication by the medium to be conveyed enters into the sliding bearing, EP 0 814 275 B1 proposes that the inside diameter of the bearing sleeves is greater than the inside diameter of the spacer sleeve. EP 0 814 275 B1 discloses that the bearing sleeve is radially centred in the cold state above the L ring of the spacer sleeve. In the warm state the centring over the extension of the shaft is taken over by the bearing sleeves. It is to be seen as a disadvantage here that particles, e.g. dirt particles can collect between the shaft and the ceramic bearing sleeve so that there is a risk that the bearing sleeves could be destroyed or could disintegrate during a thermal expansion.
Accordingly hydrodynamic sliding bearings are known the components whereof are formed from different types of materials, where for example, the bearing sleeves consist of a ceramic, e.g. of a sintered silicon carbide and the clamping sleeve or the spacer sleeve consists of a metal, e.g. a stainless steel. However, the materials exhibit different properties which should be taken into account, where for example, different (thermal) coefficients of expansion (ceramic:metal 1:4) should be mentioned. In this respect during thermal stressing of the metal-ceramic connection, stresses can occur where the metallic connection partners expand more than the ceramic connection partner. In order to mount the bearing bushing in a torque-proof manner in the bearing housing, pin solutions are known where, for example, radial bolts are provided which engage in a radial hole in the bearing bushing in the installed state of the sliding bearing, as disclosed for example in EP 0 814 275 B1.
A disadvantage with the known prior art is that the bearing bushing is very liable to failure as a result of the radial hole to be introduced since this is at least weakened by the intervention there. Furthermore, measures for axial tensioning, e.g. L-profile rings must disadvantageously be provided in order to be able to counteract different thermally induced length expansions of the different materials.